hermite.h 1.3 KB

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  1. /*
  2. * This file is part of FFmpeg.
  3. *
  4. * FFmpeg is free software; you can redistribute it and/or
  5. * modify it under the terms of the GNU Lesser General Public
  6. * License as published by the Free Software Foundation; either
  7. * version 2.1 of the License, or (at your option) any later version.
  8. *
  9. * FFmpeg is distributed in the hope that it will be useful,
  10. * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11. * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  12. * Lesser General Public License for more details.
  13. *
  14. * You should have received a copy of the GNU Lesser General Public
  15. * License along with FFmpeg; if not, write to the Free Software
  16. * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  17. */
  18. #ifndef AVFILTER_HERMITE_H
  19. #define AVFILTER_HERMITE_H
  20. static inline double hermite_interpolation(double x, double x0, double x1,
  21. double p0, double p1,
  22. double m0, double m1)
  23. {
  24. double width = x1 - x0;
  25. double t = (x - x0) / width;
  26. double t2, t3;
  27. double ct0, ct1, ct2, ct3;
  28. m0 *= width;
  29. m1 *= width;
  30. t2 = t*t;
  31. t3 = t2*t;
  32. ct0 = p0;
  33. ct1 = m0;
  34. ct2 = -3 * p0 - 2 * m0 + 3 * p1 - m1;
  35. ct3 = 2 * p0 + m0 - 2 * p1 + m1;
  36. return ct3 * t3 + ct2 * t2 + ct1 * t + ct0;
  37. }
  38. #endif /* AVFILTER_HERMITE_H */